AU6283190A - Recombinant product - Google Patents

Abstract

PCT No. PCT/AU90/00396 Sec. 371 Date May 6, 1991 Sec. 102(e) Date May 6, 1991 PCT Filed Sep. 4, 1990 PCT Pub. No. WO91/03556 PCT Pub. Date Mar. 21, 1991.This invention relates to PAI-2 and its expression as a recombinant molecule in eukaryotic cell lines as a glycosylated secreted molecule, to the constructs expressing it, to host cells expressing it, to compositions comprising it, to methods of treatment, prophylaxis and diagnosis using it and to antibodies raised against it. The invention also provides a 414 amino acid form of PAI-2 wherein the N-terminal methionine residue is deleted, a 60 kD glycosylated secreted recombinant form of PAI-2 and compositions and methods using these molecules. The invention further relates to a novel synthetic signal peptide.

Description

Recombinant Product

Technical Field The invention relates to enhanced secretion of PAI-2, to recombinant polynucleotide constructs suitable for providing enhanced secretion of PAI-2, to the expression products of those constructs and to their uses, as well as a 414 amino acid form of PAI-2, a synthetic signal peptide used in the preparation of glycosylated, secreted PAI-2 and 60 kD glycosylated, secreted, recombinant PAI-2.

Deposition of microorganisms BTA 1445, an EL. coli strain harbouring a PAI-2 encoding construct was deposited with the American Type Culture Collection of 12301 Parklawn Drive, Rockville, MD 20852 U.S.A. under the provisions of the Budapest Treaty on 11 February 1987 under accession number ATCC 53585.

Background Art Plasminogen activator (PA) inhibitor Type 2 (PAI-2) is one of four immunologically distinct groups of PA inhibitors. PA inhibitors are members of the serpin gene family.

PAI-2, also termed minactivin, has been purified from the human monocytic cell line U937 (International Patent Application PCT/AU85/00191 published as WO86/01212 and PCT/AU87/00068 published as WO87/05628) . It has also been detected in pregnancy plasma and in the conditioned medium of several human cells including peripheral blood monocytes, HT1080 fibrosarcoma cells and HEp3 laryngeal carcinoma cells, Distinct molecular weight species of PAI-2 have been identified:

A 46kD form is non-g]ycosylated and primarily cell associated. This form has been found in lysates of U937 cells and purified from the conditioned medium of phorbol ester (PMA) stimulated U937 cells (International Patent Application No. PCT/AU87/00068) . - 2 - A 60kD glycosylated form has been found to be secreted by U937 cells (Genton et al. , 1987) as well as being present in the maternal plasma of pregnant women (Lecander and Astedt, 1986). The non-glycosylated 46kD intracellular form accounts for 80-90% of PAI-2 synthesized in U937 (Genton et al. , 1987) and HT1080 cells (Medcalf et al.. 1988)

Examination of the primary amino acid sequence of PAI-2 reveals that the molecule lacks the characteristic transient signal peptide usually found at the amino (NH )-terminus of secreted proteins. Although the NH₂-terminus of the purified 46kD form of PAI-2 from U937 cells has not been determined, apparently because it is blocked (Kruithof et al, 1986), the NH₂~terminus of the 60kD glycosylated version has been reported to be the initiator methionine (residue 1, Ye et al.. 1988). This implies that secretion occurs without cleavage of a signal peptide from PAI-2. The mode of translocation of PAI-2 through the cell is not understood, however an internal signal has been proposed (Ye et al. _ 1988).

As is the case with most potent biologically active proteins, PAI-2 is produced in very small amounts in vivo and as such is difficult to purify and characterise by conventional biochemical approaches. The recent cloning of the gene for PAI-2 and its expression in bacterial cells (International Patent Application No. PCT/AU87/00068) now allows the production of significant quantities of purifed 46kD PAI-2 which is needed to evaluate its biological efficacy in clinical applications. However this bacterial material is not glycosylated, nor modified post-translationally in a manner analogous to that secreted by human cells. Therefore it is desirable to produce glycosylated forms of PAI-2 using transfected mammalian cells, since the two forms of PAI-2 may differ in their biological activities e.g. binding affinity for urokinase, PA specificity, immunogenicity, in vivo half-life etc. The native PAI-2 gene has previously been expressed in a number of heteroloαous mammalian expression systems (International Patent Application No. PCT/AU87/00068) . Although PAI-2 is synthesized in these systems, expression levels are low, and the majority of the product (approx. 90%) is non-glycosylated and intracellular. PAI-2 produced in this form is a suitable molecule for prophylactic, therapeutic and/or diagnostic uses but ^;ts use is limited by the quantities obtainable and limited glycosylation. It is still desirable to be able to attain efficient secretion, of the 60 kD glycosylated molecule, in order to be able to use the molecule for prophylactic, therapeutic and/or diagnostic purposes on a clinical scale. In addition to expression of PAI-2 in mammalian cells (International Patent Application No. PCT AU87/00068) , workers have attempted to secrete the 60 kD form of PAI-2. A Swedish group has attempted to secrete PAI-2 from transfected CHO cells but could not detect any secretion of 60 kD PAI-2 (Ny et al, 1988, Ny et al, 1989). A Swiss group attempted the secretion of PAI-2 using transfected WISH cells but likewise found that most of the PAI-2 material was of the intracellular form. Although some high molecular weight material was found in the culture medium, it was not demonstrated that the material was glycosylated (Belin, D., Wohlwend, A., and Vassalli, J.D. (1989); Belin, D., Wohlwend, A., Schleuning, W-D, Kruithof, E.K.O. and Vassalli, J.D. (1989)). The material may have been partially glycosylated because the mobility was different from U937 high molecular weight PAI-2. Previous studies have shown that the addition of a heterologous hydrophobic signal domain to the NH -terminus of a cytoplasmic protein may result in certain circumstances in the translocation of the cytoplasmic protein across the endoplasmic reticulum (Hiebert and Lamb, 1988) . Translocation across the ER is the first step along the secretory pathway. The nature of the heterologous signal peptide (e.g. whether or not it is cleaved from the protein) and the inherent properties of the cytoplasmic protein (e.g. the presence of other transport or membrane retention signals) then determine whether the chimeric protein is secreted, anchored to a cellular membrane or degraded.

Because of the complexity of the secretion mechansi it is not possible to convert in a predictable manner a cytoplasmic non-glycosylated molecule into a secreted, glycosylated molecule. Even if by the addition of a signa sequence a cytoplasmic molecule is secreted, the processin (i.e. cleavage) of the added signal sequence may occur at different unpredictable locations. Transient NH₂-terminal signal sequences found on most secreted proteins are identified by three distinct regions - a basic N-terminal region which may contain charged residues, a central hydrophobic core and a C-terminal region containing the signal peptidase recognition site.

There is no consensus sequence for signal peptidase recognition although von Heijne (1986) has developed rules that take account of many of the known cleavage sites. Th application of these rules, however, does not necessarily allow the prediction of cleavage sites when they are appli to cytoplasmic molecules bearing heterologous signal sequences.

Disclosure of the Invention In accordance with the present invention, the addition of selected or designed signal sequences to PAI-2 not only facilitates secretion of the glycosylated 60 kD form of PAI-2 but also directs correct processing of the signal. In addition, by utilising these signal sequences, PAI-2 has been secreted either with or without its N-terminal methionine residue.

Definitions

As used throughout the specification the expression "PAI-2 variant" and "variant of PAI-2" refer to a molecule derived from PAI-2 by alteration to the NH„-terminus thereof to provide an efficient signal sequence for secretion of the glycosylated molecule from a host cell. The term "parenteral" as used herein includes subcutaneous injections, intravenous, or intramuscular injection, or infusion techniques.

The term "synthetic signal peptide" as used throughout the specification refers to a peptide which is made in vitro or in vivo by translating a synthesized oligo-deoxyribonucleotide sequence.

According to a first embodiment of this invention there is provided a process for the preparation of recombinant, glycosylated, secreted PAI-2 or recombinant glycosylated secreted PAI-2 without its N-terminal methionine, which process comprises: providing a construct comprising a first polynucleotide molecule encoding PAI-2 or PAI-2 without its N-terminal methionine; and attaching a polynucleotide molecule encoding a transient signal sequence to the 5' end of the first polynucleotide molecule, such that the resulting hybrid protein expressed from the construct will consist of a transient signal sequence attached to the NH_-terminal of PAI-2 or of PAI-2 without its N-terminal methionine; and expressing the construct in a eukaryotic host cell.

The signal peptide may be attached to the N-terminal methionine of PAI-2 or alternatively the N-terminal methionine may be deleted, and the signal peptide attached to the next residue, viz glutamic acid.

The signal peptide is designed to be cleaved during translocation of the PAI-2 molecule across the endoplasmic reticulum of the host cell.

The signal peptide may be a synthetic signal peptide. Generally, the synthetic signal sequence is designed so that it has three distinct regions - a basic N-terminal region which may contain charged residues, a central hydrophobic core and a C-terminal region containing the signal peptidase recognition site. Attempts at designing signal peptidase cleavage sites can be assisted using the method of von Heijne (1986). A preferred synthetic peptide is:

M K C L L L A L G L L A F V P L V R A

The signal peptide may be naturally occurring.

A preferred natural signal peptide is the signal peptide from the protein human α-1-antitrypsin:

M P S S V S W G I L L L A G L C C L V P V S L A.

Other natural signal peptides could function in an analagous manner to the α-1-antitrypsin signal when fused to the NH_-terminus of PAI-2. According to a second embodiment of the invention there is provided a recombinant glycosylated PAI-2 encoding construct comprising a polynucleotide molecule encoding a transient signal peptide attached to the NH₂-terminal methionine or the NH_-terminal glutamic acid of PAI-2. Preferably, the construct is a DNA molecule.

According to a third embodiment of the invention there is provided a variant of PAI-2 comprising an altered NH₂-terminus wherein the NH₂-terminus of PAI-2 is altered to provide an efficient signal peptide. Typically, the alteration is in the first 22 amino acids of the amino acid sequence of PAI-2.

Preferably, all or some of the asparagine residues at positions 8 and 14, lysine at position 17, and the histidine at position 18 are replaced. Preferably replacement is by in vitro mutagenesis. Preferably the amino acids are replaced by a more hydrophobic amino acid selected from Leu, Phe, Ala, Met, Thr, Ser, lie and Val.

According to a fourth embodiment of this invention there is provided a polynucleotide molecule encoding a PAI-2 variant of the third embodiment.

Preferably, the polynucleotide molecule is a DNA molecule.

According to a fifth embodiment of this invention there is provided the synthetic peptide:

M K C L L L A L G L L A F V P L V R A. Preferably, the signal encoding sequences are prepared by DNA synthesis regardless of whether they are synthetic or naturally occurring signal sequences.

According to a sixth embodiment of the invention there is provided a recombinant DNA molecule comprising a polynucleotide molecule of the second embodiment or of the f-mrth embodiment which polynucleotide molecule is a DNA molecule, and vector DNA.

Typically, the vector DNA is plasmid DNA. Preferred plasmid vectors of the invention include pGEM4Z, pSVL, pBTA613, pBTA830 and baculovirus transfer vectors such as pAC373.

Preferred recombinant DNA molecules of the invention include pBTA822, pBTA823, pBTA825, pBTA826, pBTA827, pBTA828 and pBTA839.

According to a seventh embodiment of the invention there is provided a transformed host cell transformed by a recombinant DNA molecule of the sixth embodiment.

Typical host cell lines are derived from eukaryotic organisms and include monkey kidney COS cells, the monkey kidney cell line Vero, Chinese Hamster Ovary (CHO) cells, the human histiocytic lymphoma U937 cell line, derivatives of CHO-K1 cells, for example DG44, the hamster kidney cell line BHK-21, the human kidney cell line 293, the human epithelial cell derived line HeLa S3 and the human monocyte cell line HL60 and cell lines derived from the insects Spodoptera fruoiperda and Bombyx mori.

Preferably, the transformation is carried out by the calcium phosphate method or by electroporation. According to an eighth embodiment of this invention there is provided an expression product of a transformed host cell of the seventh embodiment. The expression product is glycosylated PAI-2 or a variant of PAI-2.

The invention also provides the 414 amino acid form of PAI-2 which lacks the N-terminal methionine of native

PAI-2 in glycosylated and unglycosylated form. In addition the invention provides for the first time recombinant, glycosylated, secreted 60 kD PAI-2.

According to a ninth embodiment of this invention there is provided a composition comprising an effective amount of an expression product of the eighth embodiment, or of the 60 kD glycosylated, secreted recombinant PAI-2, or of the 414 amino acid form of PAI-2 together with a pharmaceutically acceptable carrier, diluent, excipient, and/or adjuvant.

According to a tenth embodiment of this invention there is provided a process for preparing a recombinant DNA molecule of the sixth embodiment which process comprises inserting a DNA molecule of the second embodiment or of the fourth embodiment into vector DNA.

According to an eleventh embodiment of this invention there is provided a process for preparing a transformed host cell of the seventh embodiment which process comprises making a host cell competent for transformation and transforming said competent host cell with a recombinant DNA molecule of the sixth embodiment.

According to a twelfth embodiment of this invention there is provided a process for preparing an expression product of the eighth embodiment which process comprises culturing a transformed host cell of the seventh embodiment and separating the expression product from the culture.

According to a thirteenth embodiment of this invention there is provided a process for preparing a composition of the ninth embodiment which process comprises admixing an expression product of the eighth embodiment or 60 kD recombinant glycosylated secreted PAI-2, or the 414 amino acid form of PAI-2 with a pharmaceutically acceptable carrier, diluent, excipient, and/or adjuvant. According to a fourteenth embodiment of this invention there is provided an antibody raised against an expression product of the eighth embodiment or against recombinant secreted glycosylated 60 kD PAI-2, or against the 414 amino acid form of PAI-2, or against a composition of the ninth embodiment.

According to a fifteenth embodiment of this invention there is provided an antibody composition comprising an effective amount of an antibody of the fourteenth embodiment together with a pharmaceutically acceptable carrier, diluent, excipient, and/or adjuvant.

According to a sixteenth embodiment of this invention there is provided a method of passively vaccinating a host in need of such treatment which method comprises administering an effective amount of an antibody of the fourteenth embodiment or an antibody composition of the fifteenth embodiment., to the host.

According to a seventeenth embodiment of this invention there is provided a process for producing an antibody of the fourteenth embodiment which process comprises immunising an immunoresponsive host with an expression product of the eighth embodiment, or recombinant glycosylated secreted 60 kD PAI-2, or the 414 amino acid form of PAI-2, or a composition of the ninth embodiment. According to a eighteenth embodiment of the invention there is provided an expression product of the eighth embodiment produced by the process of the twelfth embodiment.

According to a nineteenth embodiment there is provided an antibody of the fourteenth embodiment produced by the process of the seventeenth embodiment.

The antibodies produced may be monoclonal or polyclonal antibodies. For the production of monoclonal antibodies the PAI-2 molecules of the invention are used as immunogens according to standard techniques for the preparation of monoclonal antibodies.

According to a twentieth embodiment of the invention there is provided a diagnostic kit containing an expression product, and/or composition, and/or antibody and/or antibody composition, respectively of the eighth, ninth, fourteenth and fifteenth embodiments, and/or the 414 amino acid form of PAI-2 and/or 60 kD glycosylated secreted recombinant PAI-2, together with positive and negative standards as controls.

According to a twenty-first embodiment of this invention there is provided a reagent for locating and defining the boundaries of tumours in histological specimens or in vivo which reagent compr: es a suitably labelled expression product of the eighth embodiment, or suitably labelled 60 kD recombinant secreted glycosylated PAI-2, or suitably labelled 414 amino acid form of PAI-2. According to a twenty-second embodiment of this invention there is provided a method of locating and defining the boundaries of tumours in histological specimens or in vivo which method comprises applying or administering a reagent according to the twenty-first embodiment to the specimen or patient respectively and subsequently imaging to determine the site of the concentration of the label. According to a twenty-third embodiment of this invention there is provided a method of inhibiting tumour invasion or treating tumours comprising administering to a patient requiring such treatment a therapeutically effective amount of an expression product of the eighth embodiment or a composition of the ninth embodiment or 60 kD glycosylated secreted recombinant PAI-2 or the 414 amino acid form of PAI-2 either labelled or unlabelled.

According to a twenty-fourth embodiment of this invention there is provided a method of treatment of chronic inflammation such as rheumatoid arthritis comprising administering to a patient requiring such treatment a therapeutically effective amount of an expression product of the eighth, embodiment or a composition of the ninth embodiment or recombinant glycosylated secreted 60 kD PAI-2 or the 414 amino acid form of PAI-2 either labelled or unlabelled.

Labels to be used in conjunction with 60 kD PAI-2, expression products and 414 amino acid forms of PAI-2 in accordance with this invention are those standardly used in the art for labelling for the purposes of diagnosis, n vitro detection, imaging, or therapy.

According to a twenty-fifth embodiment of this invention there is provided a method of monitoring chronic inflammation comprising the detection of PAI-2 in samples of body fluids and tissues using antibodies of the fourteenth embodiment or an antibody composition of the fifteenth embodiment.

According to a twenty-sixth embodiment of the invention there is provided a method of monitoring chronic inflammation comprising using an expression product of the eighth embodiment, recombinant glycosylated secreted 60 kD PAI-2 or the 414 amino acid form of PAI-2.

The PAI-2 variants expression products, 414 amino acid form of PAI-2 and recombinant glycosylated secreted 60 kD PAI-2 produced in accordance with this invention are of use in the following areas: therapy, prophylaxis and diagnosis of inflammatory disease; therapy, prophylaxis and diagnosis of cancer metastasis and proliferation; therapy of transplant and placenta rejection crises and graft-versus-host reactions; therapy and diagnosis of autoimmune diseases and diseases associated with excessive oxygen radical production; therapy and prophylaxis of wound and bone healing disorders, tissue damage during or after acute reperfusion, and subarahnoidal bleeding disorders; as topical medicaments for promoting fibrin adhesion, promoting healing of wounds and burns; treating asthma and treating or preventing diseases associated with high leukocyte activity; and suppression of the monocyte-macrophage system. Specific examples from the above classes of disease include: rheumatoid arthritis osteoarthritis colitis ulcerosa systemic lupus erythematosus multiple sclerosis psoriasis pemphigus corπaal and duodenal ulceration purpura periodontitis muscular dystrophy

The amount of expression product, 60 kD glycosylated secreted recombinant PAI-2 or 414 amino acid form of PAI-2 that may be combined with carrier to produce a single dosage form will vary depending upon the condition being treated, the host to be treated and the particular mode of administration. It will be understood, also, that the specific dose level for any particular patient will depend upon a variety of factors including the activity of the specific protein product or antibody employed, the age, body weight, general health, sex, diet, time of administration, route of administration, rate of excretion, drug combination, the particular state being treated and the severity of the particular condition undergoing treatment.

The compositions of the present invention may be administered parenterally or topically or potentially via mucosal routes in dosage unit formulations containing conventional, non-toxic, pharmaceutically acceptable carriers, diluents, adjuvants and/or excipients as desired. Injectable preparations, for example, sterile injectable aqueous or oleagenous suspensions may be formulated according to the known art using suitable dispersing or wetting agents and suspending agents. The sterile injectable preparation may also be a sterile injectable solution or suspension in a non-toxic parenterally acceptable diluent or solvent, for example, a solution in 1,3-butanediol. Among the acceptable vehicles and solvents that may be employed are water. Ringer's solution, and isotonic sodium chloride solution. In addition, sterile, fixed oils are conventionally employed as a solvent or suspending medium. For this purpose any bland fixed oil may be employed including sythetic mono- or diglycerides, In addition, fatty acids such as oleic acid find use in the preparation of injectables.

The term "pharmaceutically acceptable adjuvant" can mean either the standard compositions which are suitable for human administration or the typical adjuvants employed in animal vaccinations.

At present alum is the only registered adjuvant for human use however, experimental work is being conducted on other adjuvants for human use and it is anticipated that these other adjuvants would be suitable for use in preparing compositions for human vaccination in accordance with this invention. Suitable adjuvants for the vaccination of animals include but are not limited to oil emulsions such as Freund's complete or incomplete adjuvant (not suitable for livestock use), Marcol 52: Montanide 888 (Marcol is a Trademark of Esso. Montanide is a Trademark of SEPPIC,

Paris), squalane or squalene, Adjuvant 65 (containing peanut oil, mannide monooleate and aluminium monostearate), mineral gels such as aluminium hydroxide, aluminium phosphate, calcium phosphate and alum, surfactants such as hexadecylamine, octadecylamine, lysolecithin, dimethyldioctadecylammonium bromide,

N,N-dioctadecyl-N' ,N'-bis(2-hydroxyethyl) propanediamine, methoxyhexadecylglycerol and pluronic polyols, polyanions such as pyran, dextran sulfate, polyacrylic acid and carbopol, peptides and amino acids such as muramyl dipeptide, dimethylglycine, tuftsin and trehalose dimycolate. The expression products of the present invention can also be administered following incorporation into liposomes or other micro-carriers, or after conjugation to polysaccharides, proteins or polymers or in combination with Quil-A to form "Iscoms" (Immunostimulating complexes) (Morein ei_al. , Nature I , 457-460 [1984]). Other adjuvants suitable for use in the present invention include conjugates comprising the expression _ roduct together with an integral membrane protein of prokaryotic origin, such as TraT. (See PCT/AU87/00107)

Routes of administration, dosages to be administered as well as frequency of injections are all factors which can be optimized using ordinary skill in the art. Typically, the initial vaccination is followed some weeks later by one or more "booster" vaccinations, the net effect of which is the production of high titres of antibodies against the immunogen.

Compositions for topical administration include creams, ointments and pastes. The ingredients that constitute the base of ointments (e.g. petrolatum, waxes) are melted together, powdered drug components are added and the mass stirred with cooling. Generally, the product is then passed through a roller mill to achieve the - 14 - particle-size range desired for the dispersed solid. Pastes are ointments with relatively large, dispersed solid content, and are prepared similarly.

Creams are semisolid emulsions, either water-in-oil or oil-in-water. A solid ingredient can be added to the appropriate phase before emulsification or may be dispersed at some point after the emulsification step. Topical dosage forms include disc dosage form systems that have been used for transdermal delivery of therapeutic agents. They provide uniform and prolonged drug release.

It would be desirable in patients suffering from particular disease states to be able to administer the compositions of the invention either orally, rectally or possibly even vaginally. Compositions which could be used in these ways could be prepared as follows:

Suppositories for rectal or vaginal administration of the compositions of the invention can be prepared by mixing the composition with a suitable nonirritating exipient such as cocoa butter, theobroma oil, glycerinated gelatin or polyethylene glycols which are solid at ordinary temperatures but liquid at rectal or vaginal temperature or by contact with fluids present in the appropriate cavity and will therefore melt in the rectum or vagina and release the drug. Solid dosage forms for oral administration may include capsules, tablets, pills, powders, and granules. In such solid dosage forms, expression products, recombinant glycosylated secreted 60 kD PAI-2 or 414 amino acid form of PAI-2 may be admixed with at least one inert diluent such as sucrose, lactose starch or hydrolysed gelatin. Such dosage forms may also comprise, as is normal practice, additional substances other than inert diluents, e.g., lubricating agents such as magnesium stearate. In the case of capsules, tablets, and pills, the dosage forms may also comprise buffering agents. Tablets and pills can additionally be prepared with enteric coatings.

Liquid dosage forms for oral administration may include nanoparticles, microcapsules, LTB conjugates, cholera or its B subunit as a conjugate, or vitamin B12 conjugates in pharmaceutically acceptable emulsions, syrups, solutions, suspensions, and elixirs containing inert diluents commonly used in the art, such as water. Such compositions may also comprise adjuvants, such as wetting agents, emulsifying and suspending agents or TraT as a conjugate, and sweetening, flavouring, and perfuming agents including sugars such as sucrose, sorbitol, fructose etc, glycols such as polyethylene glycol, propylene glycol etc, oils such as sesame oil, olive oil, soybean oil etc, antiseptics such as alkylparahydroxybenzoate etc, and flavours such as strawberry flavour, peppermint etc.

The recombinant constructs of the invention provide expression of secreted and glycosylated forms of PAI-2.

Brief Description of Drawings Figure 1 shows the sequence of oligonucleotides and encoded signal peptides employed in construction of the in vitro and in vivo PAI-2 expression vectors. Figure 2 shows construction of in vitro expression vectors:

A: pBTA 821 containing PAI-2 gene without signal B: pBTA 822 containing PAI-2 gene with synthetic signal C: pBTA 823 containing PAI-2 gene with α-1-antitrypsin signal Figure 3 shows construction of mammalian cell expression vectors:

A: pBTA 824 containing PAI-2 gene without signal B: pBTA 825 and pBTA 827 containing PAI-2 gene with synthetic sign.- C: pBTA 826 and pBTA 82 containing PAI-2 gene with α-1-antitrypsin signal D: pBTA 839 containing PAI-2 gene with synthetic signal

Figure 4 shows the products of the PAI-2 gene and signal variants translated in a cell-free system and electrophoresed through an SDS-PAG. Figure 5 shows expression of PAI-2 gene and signal variants in transfected mammalian cells. Aliquots of the medium were immunoprecipitated with an anti-PAI-2 antibody and precipitates run on an SDS-PAG. Figure 6 shows urokinase binding to PAI-2 secreted from transfected COS cells immunoprecipitated with anti-PAI-2 antibodies and electrophoresed through an SDS-PAG.

Figure 7 shows DNA and amino acid sequence of preA-PAI2 VIZ PAI-2 plus synthetic signal. Amino acids in capitals indicate the signal sequence.

Figure 8 shows DNA and amino acid sequence of preB-PAI-2 VIZ PAI-2 plus α-1-antitrypsin signal. Amino acids in capitals indicate the signal sequence.

Figure 9 shows the digestion of the 60,000 Mr PAI-2 secreted from transfected COS cells with various glycosidases. The products were separated by SDS-PAGE.

Figure 10 shows the peaks of radioactivity released during repeated cycles of Edman degradation on labelled 60,000 Mr PAI-2 secreted from COS cells transfected with: A: pBTA 825 (contains PAI-2 gene with synthetic signal) B: pBTA 826 (contains PAI-2 gene with alpha-1 antitrypsin signal) Figure 11 shows the secretion of 60,000 Mr PAI-2 into the medium from a CHO-K1 cell line stably transfected with pBTA 827. The PAI-2 was immunoprecipitated from the medium and then fractionated by SDS-PAGE.

Best Mode of Carring Out the Invention The recombinant DNA molecules and transformed host cells of the invention are prepared using standard techniques of molecular biology.

Expression products of the invention are obtained by culturing the transformed host cells of the invention under standard conditions as appropriate to the particular host cell and separating the expression product from the culture by standard techniques. The expression product may be used in impure form or may be purified by standard techniques as appropriate to the expression product being produced.

The compositions of the invention are prepared by mixing, preferably homogeneously mixing, expression product, 60 kD recombinant secreted glycosylated PAI-2 or the 414 amino acid form of PAI-2 with a pharmaceutically acceptable carrier, diluent, excipient and/or adjuvant using standard methods of pharmaceutical preparation.

The amount of expression product, recombinant glycosylated secreted 60 kD PAI-2, or the 414 amino acid form of PAI-2 required to produce a single dosage form will vary depending upon the condition to be treated, patient to be treated and the particular mode of administration. The specific dose level r any particular patient will depend upon a variety of factors including the activity of the expression product or PAI-2 molecule employed, the agt , body weight, general health, sex, and diet of the patient, time of administration, route of administration, rate of excretion, drug combination and the severity of the condition undergoing treatment.

The composition may be administered parenterally or topically, or possibly by inhalation spray, vaginally, orally or rectally in unit dosage formulations containing conventional, non-toxic, pharmaceutically acceptable carriers, diluents, excipients and/or adjuvants as desired. Antibodies are raised using standard vaccination regimes in appropriate hosts. The host is vaccinated with an expression product, recombiⁿant glycosylated secreted 60 kD PAI-2 or the 414 amino acic form of PAI-2 or a composition of the invention.

The antibody composition is prepared by mixing, preferably homogeneously mixing, antibody with a pharmaceutically acceptable carrier, diluent, excipient and/or adjuvant using standard methods of pharmaceutical preparation. The amount of antibody required to produce a single dosage form will vary depending upon the condition to be treated, patient to be treated and the particular mode of administration. The specific dose level for any particular patient will depend upon a variety of factors including the activity of the antibody employed, the age, body weight, general health, sex, and diet of the patient, time of administration, route of administration, rate of excretion, drug combination, and severity of the condition undergoing treatment.

The antibody composition may be administered parenterally in unit dosage formulations containing conventional, non-toxic, pharmaceutically acceptable carriers, diluents, excipients and/or adjuvants as desired. Diagnostic kits are prepared by formulating expression product and/or antibodies and/or recombinant glycosylated secreted 60 kD PAI-2 and/or the 414 amino acid form of PAI-2 at appropriate concentration to the substance(s) to be detected with a pharmaceutically acceptable carrier, diluent, excipient and/or adjuvant. A positive control standard of a known concentration of the substance to be detected is prepared similarly. The negative standard comprises carrier, diluent, excipient and/or adjuvant alone. Examples of diagnostic kits include a tumour diagnostic wherein the reagent comprises anti-expression product antibodies and the positive control comprises an expression product standard of known concentration.

We have constructed two variants of PAI-2 that are efficiently secreted from mammalian cells; both contain an NH_-terminal signal designed to be cleaved during translocation across the endoplasmic reticulum (ER) . One of these signals is an artificial signal that we designed according to the above description of signal peptides. It has the sequence:

M K C L L L A L G L L A F V P L V R A The second signal is the natural signal peptide from the protein human α-1-antitrypsin:

M P S S V S W G I L L L A G L C C L V P V S L A . However it is possible that other natura l signal peptides could function in an analogous manner to the α-1-antitryρsin signal when fused to the NH_-terminus of PAI-2. The examples of signal peptides described are by way of example only and are not intended to be limiting on the scope of the invention. The first PAI-2 signal-containing variant was constructed such that the artificial signal was fused to the NH₂-terminal methionine of PAI-2. Correct cellular processing of this signal peptide should result in a mature PAI-2 molecule of 415 amino acids with Met at its NH₂-terminus. The second variant of PAI-2 was constructed by fusing the human α-1-antitrypsin signal peptide to PAI-2 without is NH_-terminal methionine. After correct cellular processing a mature PAI-2 molecule of 414 residues having a glutamic acid residue at its NH_-terminus should be generated. Details of the construction of the signal-PAI-2 molecules and their expression in both in vitro and in vivo systems are described below.

An alternative to adding heterologous signal peptides to PAI-2 in order to have PAI-2 secreted efficiently from mammalian cells could be to modify the native PAI-2 sequence. The first 22 amino acids of PAI-2 contain a stretch of hydrophobic residues characteristic of a signal peptide. However experiments below show that this region does not behave as a typical signal i.e. it does not promote translocation of PAI-2 across the ER. However, since some high molecular weight glycosylated PAI-2 has been found in culture media and plasma, residues 1-22 may represent an inefficient signal. The hydrophobic nature of the NH -terminal 22 residues of PAI-2 is compromised by 2 asparagine residues (positions 8 and 14), a lysine at position 17, and a histidine at 18. In vitro mutagenesis of this region to replace one or more of these residues with a more hydrophobic amino acid (e.g. Leu, Phe, Ala, Met, Thr, Ser, lie, Val) could improve the efficiency with which this region acts as a signal peptide. A signal peptidase recognition site is predicted after Ala₂₂. Thus these PAI-2 variants may be secreted without their first 22 residues. Although this region is conserved between member of the serpin gene family its presence may not be required for biological activity of PAI-2. Construction of Vectors for Expression of Sional-PAI-2 variants

For details of recombinant DNA techniques used see Maniatis et al (1982). Oligonucleotides encoding the signa peptides (Figure 1) were synthesized on an Applied Biosystems DNA synthesizer (Model 380A) , and purified through a polyacrylamide gel. Complementary oligonuclotide (Al and A2 or Bl and B2 or Cl and C2) were mixed in a 1:1 molar ratio and phosphorylated with 5 units T4 polynucleotide kinase in 65mM Tris-Cl pH 7.5, lOmM MgCl₂, 5mM dithiothreitol, ImM ATP. The mixture was heated to 100°C for 3 minutes and cooled slowly to room temperature t allow annealing to take place.

The annealed signal peptide oligonucleotides were ligated to the PAI-2 coding sequences and cloned into the vectors pGEM4Z (Promega) , pSVL (Pharmacia) pBTA613 and pBTA830. The first vector, pGEM4Z, is useful for expressin gene products in a cell-free transcription/translation system; pSVL is useful for transient expression in monkey kidney COS cells; pBTA613 and pBTA830 are vectors that can be selected and stably integrated in mammalian cell lines such as Chinese Hamster Ovary (CHO) cells, Vero, BHK and

U937. The signal-PAI-2 gene constructs could also be clone into any other vector designed for expression in eukaryotic cells.

The construction of the recombinant plasmids that express the native PAI-2 gene and the signal PAI-2 variants in an in vitro system and in mammalian cells is illustrated in Figures 2 and 3. The various restriction fragments ("inserts" for cloning) were prepared as follows. Restriction enzyme digests of purified plasmid DNA were carried out in buffers recommended by the supplier. Required DNA fragments were separated from the plasmid by gel electrophoresis through 0.8-1.5% Sea-Plaque agarose (FMC Corporation) in Tris-borate buffer (Maniatis et al, 1982). Fragments were visualized by staining with ethidium bromide and UV transillumination. The band of agarose containing the appropriate fragment was sliced out of the gel, melted at 65°C and the DNA was extracted by passing the diluted material through a NACS column (BRL) as recommended by the supplier. The DNA was then precipitated with ethanol in the presence of carrier tRNA (10 μg/ml) .

Vectors were typically prepared as follows. Plasmid DNA purified by CsCl density gradient centrifugation was digested with the appropriate restriction enzymes, the digest was extracted with an equal volume of phenol/chloroform (1:1) and the DNA precipitated with 2.5 volumes of ethanol. The digested DNA was resuspended in 50mM Tris-Cl pH 9.0, ImM MgCl₂, O.lmM ZnCl₂, ImM spermidine and incubated with 1-2 units calf intestinal alkaline phosphatase (Boehringer Mannheim) for 30-60 mins at 37°C. The enzyme was heat killed at 70°C for 15 mins then the DNA was extracted with phenol/chloroform and precipitated with ethanol. Ligations were carried out as follows. Vector and insert DNAs were mixed at a molar ratio of between 1:1 and 1:5 (1:10 if the insert was smaller than lOObp) in ImM ATP, lOmM MgCl₂, 5rnM DTT, 65mM Tris-Cl pH7.5 in a volume of 10-20μl. Ligations were carried out at 16° overnight with 0.5-1 unit T4 DNA ligase (Boehringer Mannheim). Ligation mixes were diluted to 30μl with dH_0 and lOμl removed for transformation into a competent E. coli K12 host (Hanahan, 1985) . Transfor ants were selected by plating onto tryptone-soya agar plates containing lOOμg/ml ampicillin.

Plasmid DNA was extracted from individual colonies (Birnboim and Doly, 1979) and the correct recombinant plasmids identified by restriction analysis. The 5' ends of the PAI-2 gene in pBTA821, 822 and 823 were sequenced to confirm that the signal peptide and methionine start codons were in frame with the remainder of the PAI-2 sequence. Sequencing was carried out on double-stranded plasmid DNA using the Sequenase DNA Sequencing Kit (USB) as described in the instruction manual. The primer used was the T7 primer (Promega) .

The plasmids and strains used in the work are summarized in Table 1. TABLE 1: Plasmids and Bacterial strains

BTA

Strain# Plasmid Host Description Signal 1702 pBTA613^A HB101^B eukaryotic expression vector

1737 PBTA839 1.3 kb Hind III- synthetic

EcoRI from pBTA-

822 in pBTA 613

1740 PBTA830 eukaryotic expression vector

1741 PBTA821 1.3kb PAI-2 gene none in pGEM4Z^C

1742 PBTA822 1.3kb PAI-2 gene synthetic in pGEM4Z

1743 pBTA823 1.3kb PAI-2 gene α-1- in pGEM4Z antitrypsi

1744 PBTA824 1.3kb Sall-Sacl none from pBTA821 in pSVL^D

1745 PBTA825 1.3kb Sall-Sacl synthetic from pBTA822 in pSVL

1746 PBTA826 1.3kb Sall-Sacl α-1- from pBTA823 in antitryps pSVL Table 1 (continued) 1747 pBTA827 1.3kb Hindlll-EcoRI synthet from pBTA822 in PBTA830

1748 pBTA828 1.3kb Hindlll-EcoRI α-1- from pBTA823 in antitry PBTA830

1613 pBTA446^A C60θλ^F PAI-2 gene in none pLK58^E

1650 pBTA641^A N4830^G PAI-2 gene in pLK58 none

1835 pBTA679 A HB101 PAI-2 gene minus 3' none untranslated region derived from pBTA438^E

1445^H pBTA438 JM109¹ 1.6kb cDNA coding none

PAI-2 cloned pUC18

constructed at Biotechnology Australia Pty Ltd (see tex below)

B See Maniatis e_t HU, 1982 C Purchased from Promega D Purchased from Pharmacia LKB Biotechnology

E Botterman and Zabeau (1985) F E. coli K12 C600λ - thiAl, thrl, leuB6, SupE(gluV)44, lacYl, fhuA21(λ) T

G Gottesman §_£ _al 1980) H Strain deposited with American Type Culture Collection,

12301 Parklawn Drive, Rockville MD 20852, USA on 11

February 1987 under accession number ATCC 53585 and described in PCT/AU87/00068

Yanisch-Perron et. __!_ (1985)

Plasmid pBTA641 can be derived from pBTA438 as follows. pBTA438 is partially digested with XhoII plus Dral and a 155 fragment isolated and ligated to vector pLK58 cut with Bglll and Smal. The resultant plasmid pBTA446 was linearized with Bglll and ligated to a synthetic double stranded 27 mer oliognucleotide having the sequence ATCT (N)₁₆ ATGGAG wherein N represents any nucleotide, containing a bacterial ribosome binding site and the initial nucleotides of the native PAI-2 gene, creating plasmid pBTA641.

PBTA679 contains a 1.3kb fragment of the PAI-2 gene (including the entire coding region). The 1.3kb fragment was derived from the 1.6kb EcoRI-Dral fragment from pBTA438 by deleting 300bρ of 3' untranslated region between the stop codon and the Dral site (at 1604) using Bal 31 nuclease. The resultant fragment with linkers ligated to either end was subcloned into the Hindlll-BamHI sites of the multiple cloning site derived from pUClδ (Yanisch-Perron e_ s_l, 1985) . The end-point of the deletion was determined by sequencing. pBTA830 is a mammalian cell expression vector. Foreign genes are expressed by cloning into the multiple cloning site (from pUClδ) flanked upstream by the SV40 early promoter and downstream by the SV40 small t intron and early polyadenylation signals. pBTA830 comprises the following fragments in order: the 345bp Pvυll-Hindlll fragment from the SV40 origin (Bethesda Research Laboratories), 51bp Hindlll-EcoRI multiple cloning sites from pUClδ, 853bp XhoI-BamHI fragment from pMSG (a eukaryotic expression vector from Pharmacia) with EcoRI and Aatll linkers (GAATTC, GGACGTCC, New England Biolabs) attached to either end, 2262bp Aatll-Eagl fragment from pBR327 (Soberon et al. 1980), 345bp PvuII-Hindlll fragment from the SV40 origin, 1320bp Hindlll-Smal fragment from Tn5 encoding neomycin phosphotransferase (Pharmacia, Beck et al, 1982), 141bp

Sau3A fragment from the SV40 small t intron region, 293bp Sau3A fragment from the SV40 early polyadenylation region, 288bp Eagl-Sall fragment from pBR327, 345bp PvuII-Hindlll fragment from the SV40 origin, 734bp Hindlll-Bglll fragment encoding mouse dihydrofolate reductase from pSV2-DHFR (ATCC 37146, Subramani et al, 1981), 141bp Sau3A fragment from SV40 small t intron region and 293bp Sau3A from SV40 early polyadenylation region. Except where indicated incompatible ends were made flush using SI nuclease or filled in with dNTPs and DNA polymerase I (Klenow) . pBTA613 is a mammalian cell expression vector. Foreign genes are expressed by cloning into the multiple cloning site flanked upstream by the SV40 early promoter and downstream by SV40 polyadenylation signals. pBTA613 comprises the following fragments in order. The 345bp PvuII-Hindlll fragment from the SV40 origin, 51bp Hindlll-EcoRI multiple cloning sites from pUClδ, 75bp

EcoRI-Aatll fragment from pBR327, 853bp BamHI-Xhol fragment from pMSG with Aatll linkers attached to both ends, 2262bρ Aatll-Eagl fragment from pBR327, 27bp oligonucleotide (GGCCCATATGATATCTCGAGACTAGTC) , 2δ8bp Eagl-Sall fragment from pBR327, 345bp PvuII-Hindlll fragment from the SV40 origin, 734bp Hindlll-Bglll fragment encoding mouse dihydrofolate reductase from pSV2-DHFR, 141bp Sau3A fragment from SV40 small t intron region and 293bp Sau3A fragment from SV40 early polyadenylation region. The Hindlll site at the 5' end of the dhfr gene was deleted using SI nuclease, other incompatible ends were made flush using SI nuclease or filled in with dNTPs and DNA polymerase I (Klenow) . In Vitro Translation

In pBTA 821, 622 and 623 the PAI-2 gene is placed downstream from the T7 RNA polymerase promoter. To generate RNA transcripts from the native PAI-2 gene and the signal variants, plasmid DNA purified on CsCl density gradients was linearized then transcribed using the commercially available Riboprobe Gene transcription System (Promega) . Where commercially available kits were used experiments were performed according to the manufacturer's instructions.

Typically plasmid DNA was linearized by digestion with EcoRI. The EcoRI digested DNA was treated with proteinase K [at 400μg/ml] then extracted with phenol/chloroform (1:1), precipitated with 2.5 vols ethanol and resuspended in lOmM Tris-Cl pH δ.0, ImM EDTA. Approximately lμg linear DNA was transcribed in a 25μl reaction containing 1 x transcription buffer (Promega) , lOmM DTT, 0.5mM each ATP, CTP, GTP, UTP, 40 units RNAsin and 7.5 units T7 RNA polymerase (Promega) at 37° for 60 mins.

The RNA transcripts were subsequently translated in a rabbit reticulocyte lysate cocktail. Typically, lμl of the transcription reaction (RNA) was added to a cocktail containing δμl rabbit reticulocyte lysate (Amersham) , 12.5μCi ³⁵S-Methionine (SJ1015 Amersham, lOOOCi/mmole), 20μM amino acid mix minus Met, 20 units RNAsin in a total volume of 12.5μl. In some experiments lEq microsomes

(Promega) was also included in the translation reaction. Incubation was at 30°C for lhr.

Following translation, aliquots were removed for further treatment or analysis by SDS-polyacrylamide gel electrophoresis.

To identify whether the synthetic or heterologous natural signal peptides attached to the NH₂-terminal end of PAI-2 were functioning and processed correctly, the reticulocyte lysate translation mix was supplemented with dog pancreatic microsomal vesicles (Promega) . Microsomes are generated from endoplasmic reticulum (ER) and allow signal peptide cleavage, protein translocation and core glycosylation events to be studied. Any core carbohydrates added to asparagine residues in PAI-2 molecules on translocation across the ER are removed by digesting the translation products with endoglycosidase H. The extent of translocation of a protein across the membrane is assessed by incubating the processed in vitro translation products with proteinase K. Any of the protein not fully translocated into the lumen of the microsomal vesicle is liable to be digested by proteinase K.

Endoglycosidase H digests were carried out by incubating 2μl translation mix plus 4μl RIPA buffer (1% Triton X100, 1% sodium deoxycholate, 0.1% SDS, 150mM NaCl, ' 50mM Tris-Cl pH7.5, 5mM EDTA) plus lμg aprotinin with

2mUnits Endo H (Boehringer Mannheim) in a lOμl reaction at 37° for lhr. Proteinase K digests were carried out as follows. 2μl translation mix plus 5μl phosphate buffered saline plus 0.lμg/μl proteinase K were incubated on ice for 60 mins. In some reactions lμl 1% Triton X-100 was included. Samples were boiled in 1.5% SDS, 1% 2-mercaptoethanol before electrophoresis on 10% polyacryla ide-SDS gels.

Figures 4A and 4B show the results of typical cell-free translation experiments. The autoradiogram in Figure 4B shows that the primary translation product of the native PAI-2 gene (pBTA821) consists of a 43,000 Mr molecule (Fig 4B lane b) . It is not translocated into the microsomes since proteinase K digests the product whether microsomes were present (Fig. 4B lane d) or absent (Fig. 4B lane a). Also the native product is not glycosylated since digestion with endoglycosidase H (Figure 4A lane d) has no effect on the migration of the Mr 43,000 product. This 43,000 Mr product was also immunoprecipitated with anti-PAI-2 monoclonal antibody. In contrast the primary translation products of both signal-PAI-2 variants (pBTA822 and pBTA823, see Figure 4A, lanes g and 1) have higher molecular weights (44,000-45,000) than the native PAI-2 (Fig. 4A, lane b) due to the additional signal peptide. When microsomes are included in the reaction, the translation products of pBTA822 and pBTA823 migrate more slowly (Mr 45,000-46,000) due to processing of the signal and addition of carbohydrates. There are two distinct products (44,500 and 46,000 Mr) which are fully protected from digestion with proteinase K (Figure 4B, compare lanes i and j , or o and p) . Both these products are reduced in size when digested with Endo H (Figure 4A, compare lanes h and i or m and n) to 43,000 and 41,000 Mr. These results indicate that the addition of either signal peptide to PAI-2 allows PAI-2 to be translocated across the endoplasmic reticulum membrane and to be glycosylated. Furthermore the added signal is cleaved off during translocation. - 2δ - Transient Expression In Mammalian Cells

For details of tissue culture techniques used see Freshney (1987) . To determine whether the signals attached to PAI-2 enhanced the processing and secretion of PAI-2 from mammalian cells, the native PAI-2 and the two signal variant PAI-2 genes were placed downstream of the SV40 late promoter in the eukaryotic expression vector pSVL (Pharmacia) . The construction of these vectors pBTA824, pBTA825 and pBTA826 was described above and is summarized in Figure 3. Plasmids pBTA824, pBTAδ25, pBTAδ26 were transfected into the monkey kidney COS cell line by the calcium phosphate method (Spandidos and Wilkie, 1984). Approximately 6 x 10 5 cells were seeded into a 100mm culture dish in 10ml Dulbecco's modified Eagle medium supplemented with 10% (v/v) foetal calf serum, 2mM glutamine, 50IU ml penicillin and 50μg/ml streptomycin.

Ten micrograms of CsCl purified DNA was precipitated with calcium phosphate and added to the cells. After 4 hrs the cells were treated to a glycerol shock and cultured in the above medium for about 42hrs.

To assay for expression and secretion of PAI-2 from these cells, the medium was removed about 42 hrs after glycerol shock and replaced with Eagles minimal essential medium lacking methionine (Flow) supplemented with lOOμCi/ml 35S-methionine (Amersham SJ1015 lOOOCi/mmole) . After 4 hrs of metabolic labelling the medium was collected for analysis and the cells washed with an ice cold phosphate buffered saline solution, harvested and lysed. Cells were lysed in 1% Triton X100, 0.1% SDS, 150mM NaCl, 50mM Tris-Cl pH7.5, 5mM EDTA. PAI-2 was immunoprecipitated from aliquots of medium and cell lysates by incubating with 25μg/ml anti-PAI-2 mouse monoclonal antibody (MAI-21, Biopool) at 4°C overnight in a solution containing 1% Triton X100 and lOμg/ml aprotinin. Antibody-PAI-2 complexes were extracted with 20μl anti-mouse IgG-agarose beads (Sigma) in lOmM sodium phosphate pH7.2, 0.5M NaCl. The PAI-2 was eluted from the beads with 0.15M NaCl/O.lM glycine pH2.4, analysed by SDS-polyacrylamide gel electrophoresis under reducing conditions and visualized by autoradiography as shown in Figure 5. Some cells were incubated with 5μg/ml tunicamycin for 18 hrs prior to and during the labelling, to prevent N-linked glycosylation.

Recombinant PAI-2 is seen in Fig 5, lanes f and h as a broad band of Mr 53,000-60,000. These are samples of medium from cells transfected with the synthetic signal-PAI-2 gene (pBTA825) and α-1-antitrypsin signal-PAI-2 gene (pBTAδ26) respectively. The medium from mock transfected cells (i.e. no added DNA) and from cells transfected with the vector alone (pSVL) contain no 60,000 Mr material (lanes b and c) . However a small amount of 60,000 Mr material and a larger amount of 43,000 Mr material is present in the medium from pBTAδ24 transfected cells (lane d) . The 43,000 Mr material appears not to be glycosylated (compare lanes d and e) .

Clearly the addition of the signal peptide to the PAI-2 molecule greatly € lances the secretion of the 60,000 Mr glycosylated form from COS cells.

The biological activity of the 58-60,000 Mr forms of PAI-2 were determined by a urokinase (uPA) binding assay.

Urokinase (45 IU Low Mol Wt, American Diagnostica) was added to an aliquot of medium containing 35S-labelled PAI-2 from transfected COS cells. Binding was allowed to proceed at room temperature for 90 mins. The uPA-PAI-2 complexes were immunoprecipitated from the reaction using goat anti-PAI-2 antibodies or rabbit anti-uPA serum and a solid phase 2nd antibody. Material was eluted from the immunobeads by boiling in a buffer containing 1.5% SDS and 1% (v/v) 2-mercaptoethanol and then analysed under reducing condi ions by SDS-PAGE.

Figure 6 shows the results of such an experiment. The Mr 43,000 nonglycosylated PAI-2 released from COS cells transfected with the native gene (Fig 6, lane c) forms a Mr 76,000 complex when uPA is added (Fig 6, lane d) . The 58-60,000 glycosylated PAI-2 secreted from COS cells transfected with either of the signal-PAI-2 constructs also binds uPA and a complex of Mr around 89,000 is formed (Fig. 6, lanes f and h) . This complex is immunoprecipitable with both anti-PAI-2 and anti-uPA antibodies. This demonstrates that the 58-60kD glycosylated and secreted form of PAI-2 is biochemically active. Carbohydrate Attachment

To determine the nature of the carbohydrates attached to the 60,000 Mr PAI-2, the material secreted from COS cells was digested with a variety of endoglycosidases (see Glycanalysis Systems Manual from Genzyme Corp. USA). The 60,000 Mr form was immunoprecipitated from the medium of cells transfected with pBTA826 as described above. Aliquots of this material were digested as follows.

(a) 1% Triton X-100, 1% Na deoxycholate, 0.1% SDS, 150mm NaCl, 50mM Tris-Cl pH 7.5, 5mM EDTA, 2mUnits Endoglycosidase H (Boehringer Manneheim) at 37°C for lhr. (b) 1% Triton X-100, 0.1% SDS, lOmM Na phosphate pH7.2, 400 mUnits glycopeptidase F (Boehringer Mannheim) at 37° for lhr. (c) 1% triton X-100, 0.1% SDS, lOmM D-galactono γ lactone, lOmM Na phosphate pH7.2, lm Unit neuraminidase and/or lmU endo-α-N-acetylgalactosaminidase (Boehringer Mannheim) at 37° for lhr. After digestion the products were analysed by SDS-PAGE and autoradiography. Digestion with endo H had no effect on the mobility of 60,000 Mr PAI-2 (Figure 9, lane B) indicating that any N-linked carbohydrate contained complex sugars added in the Golgi. However digestion with glycopeptidase F (which removes all N-linked carbohydrate) reduced the 60,000 Mr material to a doublet of Mr 49,000 and 50,000 (Figure 9, lane C) . These forms have higher molecular weights than unglycosylated PAI-2 (43,000 Mr). The possibility that some O-linked carbohydrate was also attached to PAI-2 was confirmed by digesting the 60,000 Mr form with glycopeptidase F, neuraminidase and endo-α-N-acetyl galactosaminidase (which removes 0-linked sugars). The combination of these three enzymes reduced the 60,000 Mr form to a 43,000 Mr form (Figare 9, lane E) , the size of unglycosylated PAI-2 (Figure 9 lane F) .

NH₂ Terminal Determination

To determine the NH_-terminal residue of the secreted 60,000 Mr form of PAI-2, 35S-methionme or

3H-leucine labelled material secreted from transfected COS cells were subjected to immunoprecipitation using the anti-PAI-2 mouse monoclonal antibody (MAI-21, Biopool) as described above. An aliquot of the 35S-Met labelled PAI-2 recovered from the medium was analyzed by SDS-polyacrylamide gel electrophoresis and shown to contain 60,000 Mr material.

The ³⁵S-Met labelled 60,000 Mr PAI-2 was applied to the

Applied Biosystems Protein Sequencer (Model 470A) and subjected to repeated cycles of Edman degradation (see

Instruction Manual for Protein Sequencer) . Fractions from each cycle were collected and counted in a Liquid Scintillation Counter. The results of this analysis (Figure 10A) indicated that the NH_ terminal residue of the 60,000 Mr PAI-2 secreted from COS cells transfected with pBTA825 is Met.

The H-leu labelled 60,000 Mr forms of PAI-2 were electrophoresed through an SDS-polyacrylamide gel and transferred to Pro Blot PVDF membrane by electroblotting (Matsudaira, 19δ7) . A fragment of the membrane containing the 60 kDa PAI-2 was excised and then applied to the Protein sequencer and sequenced as above with modifications to the Sequencer program as described by Speicher, 1989.

The results (Figures 8A, 8B) indicated that the 60,000 Mr PAI-2 secreted from COS cells transfected with pBTAδ25 has Leu residues at positions 4, 10 and 13, i.e. the synthetic signal peptide has been cleaved to leave PAI-2 with Met at its NH₂-terminus. However, the 60,000 Mr PAI-2 secreted from COS cells transfected with pBTA626 has Leu residues at positions 3, 9 and 12. This indicates that the alpha-1-antitrypsin signal has been cleaved off leaving a glycosylated PAI-2 molecule with Glu at its NH_-terminus. These results demonstrate that the signal peptides have been cleaved during processing of PAI-2 through the cell, that cleavage of the synthetic signal peptide occurs between Ala 19 and Met 20 (Figure 7), that cleavage of the alpha-1-antitrypsin signal occurs between Ala 24 and Glu 25 (Figure δ) . The 60,000 Mr PAI-2 secreted from COS cells transfected with pBTAδ25 is 415 amino acid residues. However, the 60,000 Mr PAI-2 secreted from COS cells transfected with pBTAδ26 contains 414 amino acid residues. Stable Expression in Mammalian Cells

For details of tissue culture techniques used see Freshney (1967). The stable expression of PAI-2 genes integrated into host cell genomes was investigated in various cell lines. Cell line CHO-K1 (ATCC CCL 61) is derived from a Chinese hamster ovary cell. Cell line U937 is the human monocyte-derived cell which expresses PAI-2 and from which the PAI-2 gene was isolated (Antalis et al. 1988) . Other host cells for the expression of PAI-2 include the hamster kidney cell line BHK-21 (ATCC CCL10), the human kidney cell line 293 (ATCC CRL1573), the human epithelial cell-derived line HeLa S3 (ATCC CCL2.2), and the human monocyte cell line HL60 (ATCC CCL 240) and insect cell lines derived from Spodoptera fruoiperda (Sf9, ATCC CRL1711) and Bombyx mori (Maeda et al. 1984). The PAI-2 genes with added signal sequences were inserted into the vector pBTA830 which contains the mouse dhfr gene and the gene conferring resistance to the aminoglycoside antibiotic, G418 (Figures 3B and 3C) . The resultant plasmids pBTA827, pBTA828, were transfected into the above cell lines by the calcium phosphate method

5 described, using 20μg plasmid DNA/2 x 10 cells and a . total of 3 x 10 , or by electroporation. Electroporation was carried out using lOμg linearized plasmid DNA/107 cells suspended in phosphate buffered saline/272 mM sucrose, pH 7.4, at 4°C, and pulses of 150-300V at a capacitance of

250μFD (Ausubel et al, 1987). The apparatus used was a Bio-Rad Gene Pulser.

The selection of transfectants of the CHO-K1 cell line was achieved in the nucleoside-free alpha modification of Eagles medium (αMEM) containing 2% (v/v) dialysed foetal bovine serum and 400μg/ml G418. This regime selected for both the dhfr and the G418-resistance genes present in the PAI-2 encoding plasmid. Selection of transfectants of other cell lines was done with αMEM or RPMI 1640 medium (CytoSystems) containing 2-10% foetal bovine serum and 400μg/ml G418. After selection, the PAI-2 genes were amplified along with cotransfected (and host) dhfr genes by exposure of the cultures to increasing levels of methotrexate from 0.lμM to 10μM over three months as described by Zettlemeisl et .al. (1987).

The resultant transfected cultures with stably integrated, amplified PAI-2 genes were examined for the secretion of PAI-2 into serum-free culture medium by an ELISA (Biopool, Sweden) performed according to the manufacturers instructions. Different cultures (pools) containing cells originating from many hundreds of transfection events were assayed by ELISA and the pools with the highest PAI-2 expression were chosen. The identity of the molecular weight forms of PAI-2 secreted from these cultures was verified by immunoprecipitation of culture supernatants and SDS-polyacrylamide gel electrophoresis as described above. High molecular weight, glycosylated forms of PAI-2 are produced by representative cultures as shown in Figure 11. The biological activty of the secreted forms of PAI-2 can be determined usiπj a coupled photometric assay for plasminogen activator(Cole an and Green, 1981) . The first step of the reaction involves the activation of purified plasminogen to plasmin by uPA. The activity of plasmin is then detected by the formation of a yellow thiophenolate anion. PAI-2 activity is expressed in Ploug units/ml. Finally, clones of individual cells from the highest expressing cell pool are isolated by the limiting dilution method (Freshney, 1987) . Cell colonies are assayed for PAI-2 by transferring them to nylon filters as described by Raetz et al. (1982) and detecting PAI-2 by Western blot analysis. Colonies with maximal PAI-2 expression are isolated, re-cloned, and the secreted forms of PAI-2 verified as described above.

The stable expression of PAI-2 genes integrated into host genomes was investigated further in various cell lines including CHO,DG44 and Vero. Cell line DG44 is a derivative of the Chinese hamster ovary cell CHO-K1 and contains a deletion of the gene for dihydrofolate reductase (dhfr. Urlaub et al., 1986). Vero is derived from an African green monkey kidney cell (ATCC CCL81) .

The PAI-2 gene with added signal sequence was inserted into the vector pBTA613 which contains the mouse dhfr gene (Figure 3D) . The resultant plasmid ρBTA839 was transfected into the above cell lines by the calcium phosphate method described, using lOμg plasmid DNA/2 x 10 cells and a total of 2 x 10 cells, or by electroporation. Electroporation was carried out as described by Barsoum (1990) using the Bio-Rad Gene Pulser.

The selection of transfectants of cell line DG44 was achieved in the nucleoside-free medium ocMEM (CytoSystems) containing 2% (v/v) dialysed foetal bovine serum and 0.1-0.5μM methotrexate. The selection of transfectants of Vero cells was done in the same medium. This procedure selects for transfectants with an elevated number of copies of integrated plasmid. After selection, the PAI-2 genes were amplified along with cotransfected (and host) dhfr genes by exposure of the cultures to increasing levels of methotrexate up to 10μM as described by Zettlemeisl et al (1987). The resultant transfected culture with stably integrated, amplified PAI-2 genes are examined for the secretion of PAI-2 into the serum-free culture medium by an ELISA for PAI-2 (Biopool, Sweden) performed according to the manufacturers instructions. Single colonies arising from the transfection and pools containing cells originating from many thousands of transfection events are assayed by ELISA and those with the highest PAI-2 expression are chosen. The identity of the molecular weight forms of PAI-2 secreted from these cultures is verified by immunoprecipitation of culture supernatants and SDS-polyacrylamide gel electrophoresis as described above.

Clones of individual cells are also isolated from the highest expressing cell pool by limiting dilution method (Freshney, 1987) . Cell colonies are assayed for PAI-2 by transferring them to nylon filters as described by Raetz et al. (1982) and detecting PAI-2 by Western blot analysis. Colonies with maximal PAI-2 expression are isolated, re-cloned, and the secreted forms of PAI-2 verified as described above.

Absence of Efficient Signal Sequence from Native PAI-2

The in vitro translation experiment with microsomes has for the first time demonstrated that native PAI-2 does not contain a signal sequence that is efficiently recognized by the protein translocation machinery present in some mammalian cell extracts. This may explain the observations that PAI-2 is predominantly an intracellular protein. The little material that is secreted is often unglycosylated and may be released from the cells by an unknown mechanism which does not involve transport of PAI-2 through the normal secretory pathway of the ER and Golgi. However high Mr forms of PAI-2 have also been observed; hence PAI-2 must have the capacity to translocate into the ER and Golgi (where addition of carbohydrate occurs) . The signal to allow this has not been identified. Given the results with the in vitro system described above any signal in native PAI-2 must be very inefficiently recognized by the signal recognition protein. To overcome this problem, and to ensure efficient secretion of large amounts of high molecular weight forms of PAI-2 from mammalian cells we have added a signal peptide to the NH₂-terminus of PAI-2. Results described above show that either an artificial signal peptide or a natural signal peptide can be attached to PAI-2 to create a molecule which. is translocated across the endoplasmic reticulum. The signal is cleaved and PAI-2 is processed through the secretory pathway. These high molecular weight forms of PAI-2 are glycosylated and bind to uPA.

Purification

The secreted PAI-2 is purified using established and published procedures (see International Patent Application No. PCT/AU87/00068) .

Industrial Applications The expression products, secreted glycosylated recombinant 60 kD PAI-2 and the 414 amino acid form of PAI-2 of the invention are of use as diagnostic or therapeutic substances in the fields of: therapy, prophylaxis and diagnosis of inflammatory disease; therapy, prophylaxis and diagnosis of cancer metastasis and proliferation; therapy of transplant and placenta rejection crises and graft-versus-host reactions; therapy and diagnosis of autoimmune diseases and diseases associated with excessive oxygen radical production; therapy and prophylaxis of wound and bone healing disorders, tissue damage during or after acute reperfusion, and subarahnoidal bleeding disorders; as topical medicaments for promoting fibrin adhesion, promoting healing of wounds and burns; treating asthma and treating or preventing diseases associated with high leukocyte activity; and suppression of the monocyte-macrophage system. Specific examples from the above classes of disease include: rheumatoid arthritis osteoarthritis colitis ulcerosa systemic lupus erythematosus multiple sclerosis psoriasis pemphigus corneal and duodenal ulceration purpura periodontitis muscular dystrophy

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International Patent Application PCT/AU85/00191.

International Patent Application PCT/AU87/00068.

International Patent Application PCT/AU87/00107

Claims (46)

1. A process for the preparation of recombinant, glycosylated, secreted PAI-2 or recombinant, glycosylated, secreted PAI-2 without its N-terminal methionine, which process comprises: providing a construct comprising a first polynucleotide molecule encoding PAI-2 or PAI-2 without its N-terminal methionine; attaching a polynucleotide molecule encoding a transient signal sequence to the 5' end of the first polynucleotide molecule, such that the resulting hybrid protein expressed from the construct will consist of a transient signal sequence attached to the NH_-terminal of PAI-2 or PAI-2 without its N-terminal methionine; and expressing the construct in a eukaryotic host cell.

2. A polynucleotide construct encoding a transient signal peptide attached to the NH₂-terminal methionine or the NH_?-terminal glutamic acid of PAI-2.

3. A polynucleotide construct according to claim 2 wherein the signal peptide is

M K C L L L A L G L L A F V P L V R A.

4. A polynucleotide construct according to claim 2 wherein the signal peptide is the signal peptide from the protein human α-1-antitrypsin.

5. A polynucleotide construct according to any one of claims 2 to 4 wherein the construct is a DNA molecule.

6. A variant of PAI-2 comprising an altered NH₂-terminus, wherein the NH₂-terminus of PAI-2 is altered to provide an efficient signal peptide.

7. A variant of PAI-2 according to claim 6 wherein the NH„-terminus of PAI-2 is altered in at least one position in amino acids 1 to 22 of the NH„-terminus of PAI-2.

8. A variant of PAI-2 according to claim 6 or 7 wherein all or some of asparagine residues 8 and 14, lysine residue 17 and histidine residue 18 are replaced.

9. A variant of PAI-2 according to claim 8 wherein the residue or residues are replaced by means of in vitro mutagenesis.

10. A variant of PAI-2 according to claim 8 or 9 wherein the residues are replaced by an amino acid selected from Leu, Phe, Ala, Met, Thr, Ser, lie and Val.

11. A polynucleotide molecule encoding a PAI-2 variant according to any one of claims 6 to 10.

12. A polynucleotide molecule according to claim 11 wherein the molecule is a DNA molecule.

13 . The synthetic peptide having the sequence : M K C L L L A L G L L A F V P L V R A

14. A recombinant DNA molecule comprising a DNA molecule according to claim 5 or 12 and vector DNA.

15. A recombinant DNA molecule according to claim 14 wherein the vector DNA is plasmid DNA.

16. A recombinant DNA molecule according to claim 15 wherein the plasmid DNA is selected from:

PGEM4Z, pSVL, PBTA613, pBTA830 and baculo virus transfer vectors.

17. A recombinant DNA molecule selected from pBTA822, PBTA823, pBTA825, pBTA826, pBTA827, pBTA828 and pBTA839.

18. A transformed host cell transformed by a recombinant DNA rcolecule according to any one of claims 14 to 17.

19. A transformed host cell according to claim 18 wherein the host cell is a cell of a cell line derived from a eukaryotic organism selected from monkey kidney COS cells, the monkey kidney cell line Vero, Chinese hamster ovary cells, the human histiocytic lymphoma U937 cell line, a derivative of '" O-Kl cells, DG-44, the hamster kidney cell line BHK-21, th.. human kidney cell line 293, the human epithelial cell derived line HeLa S3, and the human monocyte cell line HL60 and cell lines derived from the insects Spodoptera fruoioerda and Bombyx mori.

20. An expression product of a transfo ed host cell according to claim 18 or claim 19, comprising glycosylated PAI-2 or glycosylated PAI-2 without its N-terminal methionine, or a variant of PAI-2.

21. A PAI-2 molecule of 414 amino acids in length commencing with Glu-2.

22. The PAI-2 molecule of claim 21 in glycosylated form.

23. Recombinant glycosylated secreted 60 kD PAI-2.

24. A composition comprising an effective amount of an expression product according to claim 20, or a PAI-2 molecule according to any one of claims 21 to 23 together with a pharmaceutically acceptable carrier, diluent, excipient and/or adjuvant.

25. A process for preparing a recombinant DNA molecule according to any one of claim 14 to 17 which process comprises inserting a DNA molecule according to claim 5 or claim 12 into vector DNA.

26. A process for preparing a transformed host cell according to claim 18 or 19 which process comprises making a host cell competent for transformation and transforming said competent host cell with a recombinant DNA molecule according to any one of claims 14 to 17.

27. A process for preparing an expression product according to claim 20 which process comprises culturing a transformed host cell according to claim 18 or 19 and separating the expression product from the host cell.

28. A process for preparing a composition according to claim 24 which process comprises admixing an expression product according to claim 20 or a PAI-2 molecule according to any one of claims 21 to 23 with a pharmaceutically acceptable carrier, diluent, excipient and/or adjuvant.

29. An antibody raised against an expression product according to claim 20 or against a composition according to claim 24 or against a PAI-2 molecule according to any one of claims 21 to 23.

30. An antibody composition comprising an effective amount of an antibody according to claim 29 together with a pharmaceutically acceptable carrier, diluent, excipient and/or adjuvant.

31. A method of passively vaccinating a host in need of such treatment against PAI-2 which method comprises administering an effective amount of an antibody according to claim 29 or an antibody composition according to claim 30 to the host.

32. A process for producing an antibody according to claim 29 which process comprises immunising an immunoresponsive host with an expression product according to claim 20 or a composition according to claim 24 or a PAI-2 molecule according to any one of claims 21 to 23.

33. An expression product according to claim 20 produced by the process according to claim 27.

34. An antibody according to claim 29 produced by a process according to claim 32.

35. A diagnostic kit containing an expression product according to claim 20 and/or a composition according to claim 24 and/or a PAI-2 molecule according to any one of claims 21 to 23 and/or an antibody according to claim 29 and/or an antibody composition according to claim 30 together with a positive and a negative standard.

36. A method for locating and defining the boundaries of tumours in histological specimens which method comprises applying a suitably label¹ed expression product according to claim 20 or PAI-2 mo ule according to any one of claims 21 to 23 to the specimen and subsequently imaging to determine the site of concentration of the label.

37. A method for locating and defining the boundaries of tumours in vivo which method comprises administering a suitably labelled expression product according to claim 20 or PAI-2 molecule according to any one of claims 21 to 23 to a patient in need of such treatment and subsequently imaging to determine the site of concentration of the label.

38 A reagent for locating and defining the boundaries of tumours in histological specimens or in vivo which reagent comprises a suitably labelled expression product according to claim 20 or PAI-2 molecule according to any one of claims 21 to 23.

39. A method of inhibiting tumour invasion or treating tumours comprising administering to a patient requiring such treatment, a therapeutically effective amount of an expression product according to claim 20 or a PAI-2 molecule according to any one of claims 21 to 23 or a composition according to 24 either in labelled or unlabelled form.

40. A method of treatment of chronic inflammation comprising administering to a patient requiring such treatment a therapeutically effective amount of a expression product according to claim 20 or a PAI-2 molecule according to any one of claims 21 to 23 or a composition according to claim 24 either in labelled or unlabelled form.

41. A method of monitoring chronic inflammation comprising detecting PAI-2 in samples of body fluids and tissues using an antibody according to claim 29 or an antibody composition according to claim 30.

42. A method of monitoring chronic inflammation in body fluid and tissues comprising using an expression product according to claim 20, a PAI-2 molecule according to any one of claims 21 to 23 or a composition according to claim 24.

43. A method for the therapy, propylaxis or diagnosis of cancer metastasis and/or proliferation which method comprises the use of an expression product according to claim 20, a PAI-2 molecule according to any one of claims 21 to 23 or a composition according to claim 24.

44. A method for the therapy, propylaxis or diagnosis of an immunosuppressant condition which method comprises the use of an expression product according to claim 20, a PAI-2 molecule according to any one of claims 21 to 23 or a composition according to claim 24.

45. A method for the therapy of wounds or bone injuries which method comprises the use of an expression product according to claim 20, a PAI-2 molecule according to any one of claims 21 to 23 or a composition according to claim 24.

46. A method for the therapy, propylaxis or diagnosis of disease associated with high leukocyte activity which method comprises the use of an expression product according to claim 20, a PAI-2 molecule according to any one of claims 21 to 23 or a composition according to claim 24.